In fairness, some of those are quite a stretch. Sure, there are vague similarities (colours, approximate shapes) which might have given you a sense of familiarity but I wouldn't say - for example - that moby and docker were that similar despite the familiar artistic styles. For starters, they're not even the same animal.
My point is that if you started a containerization startup called Moby using that logo, people would be upset.
Docker doesn't own whales in the same way Apple doesn't own the concept of apples (as much as they'd like to), but using "inspired by" logos in the same context as the logo you were inspired by can cause problems.
I would disagree that the examples you provide are similar. Perhaps similar in the sense that they use the same animal. Take Mr Jumbo and PHP, style is completely different, colour is similar, but then again it's the colour of an elephant. One is wearing a top hat, the other isn't.
cosmos and CircleCI, do you actually think they are similar? watchbob and datadog? Come on.
Mr Jumbo/PHP doesn't use an elephant logo. Is it the color you're concerned with? Mr Jumbo reminds me more of Bing Bong from Inside Out.
Foxy/Gitlab logo is _very_ close.
Moby/Docker is a stretch but I can see it a bit.
Steps/Webpack isn't that close. It looks closer to the old Windows Registry icon to me.
Fall/Endomondo seems like an obvious ripoff.
Apple I see no problem with (conceptually, at least. I wouldn't personally use something with an apple in the name/logo for obvious reasons.
Cosmos/CircleCI ehhhh, it reminds me more of the Colorado stickers I see all over, even using similar colors.
Watchbob/Datadog in no way are close aside from having dogs. Datadog has a very distinct, happy puppy look to it. It looks more like some sort of Jenkins clone in dog form to me, but it's distinct enough.
Most of these are more of a stretch to me than anything, although two of them do seem to be almost clones.
The only ones that really could run afoul of anything are foxy, moby, and charlie. The rest seem pretty unique. Anything is going to start getting congested when you have hundreds and hundreds or startups looking for unique identifiable items.
